简介:阶段PVDF水晶结构和在先存在的阶段PVDF球粒以内的豌豆的结晶化上的豌豆的效果被光显微镜学OM,红外线的光谱学红外和扫描电子显微镜学SEM调查了。结果证明阶段PVDF球粒由展出高度弄弯的像滚动的形态学的lamellae组成并且在充满豌豆的混合优先地发展。与增加豌豆集中,滚动直径增加和滚动更好与对方被分开。豌豆在interspherulitic区域使第一结晶,transcrystalline层发展。随后,豌豆的transcrystalline层继续在阶段PVDF球粒以内成长,例如在在滚动之间的区域,直到在另外的豌豆transcrystalline层或球粒上侵犯。结晶化动力学结果显示在阶段PVDF的intraspherulitic区域的豌豆晶体的生长率与阶段PVDF的结晶化温度与豌豆,而是否定豌豆的内容显示出积极关联。
简介:Ithasbeenwellknownthatfluorinatedpolyurethanesexhibituniquelylowsurfaceenergy,biocompatibilityandbiostability,thermalandoxidativestabilityandnonstickingbehavior.Consequently,thesepolymershaveattractedconsiderableinterest.However,themechanicalpropertiesoffluorinatedpolyurethanesusuallydeclinewithincreasingfluorinecontents.Theblendingoffluorinatedpolyurethaneswithnormalpolyurethanewascarriedouttoachievebalancedmechanicalandsurfaceproperties.Itwasfoundthatpolyurethanewithgoodmechanicalpropertiesandlowsurfaceenergycanbeobtainedbyaddingasmallamountoffluorinatedpolyurethane.Thefluorinatedsidechainscaneasilymigratetouppermostsurfacesoftheblendsuntillthefluorinelevelatthesurfacebecomesalmostsaturated.Ithasbeenshownfromcontactangle,XPSandAFMmeasurementsthatonlyaslittleas0.34wt%offluorinelevelisenoughtoproduceasurfacesaturatedwithfluorine,andthefluorinelevelattheuppermostsurfaceisonehundredtimeshigherthanthatintheblendbulk.Thefinaloutersurfacestructuresofthepolyurethaneblendwereindependentofthecontentofthefluorinatedpolyurethaneintheblendsduetothesurfacessaturatedbyfluorine.
简介:Anovelsmallband-gapconjugatedpolymer-poly[(3-acetylpyrrole-2,5-diyl)(4-dimethylaminobenzyliene)(3-aeetylpyrrolequinodimethane-2,5-diyl)](PAPDMABE)-anditsprecursorweresynthesizedbyasimplemethodandcharacterizedby1H-NMR,FT-IR,TGAandUV-VIS.ThepolymercanbedissolvedinstrongpolarsolventssuchasDMSO,DMForNMP.Theband-gapenergyofPAPDMABEwasfoundtobe0.95eV.Theconductivityofdopedproductswithiodinefallsintherangeofasemiconductor.``
简介:3-Ethynyl-4-(trimethylsilyl)thiophene(1a)and3-ethynyl-4-bromothiophene(1b)selectivelyundergoacetylenepolymerizationsinthepresenceoftheMoCl5-andWCl6-Ph3SiHcatalyststogivesoluble,high-molecular-weightpoly(thienylacetylenes)(2)(Mwupto602000)inhighyields(upto100%).LighttransmissionspectraofTHFsolutionsof2continuouslyred-shiftwithincreasingconcentration.Theconcentratochromismshowsalogarithmicconcentrationdependence;thatis,theopticaltransitionsof2arepredictablytunablebysimplychangingtheirconcentrations.
简介:Poly(4-vinylpyridine)(P4-VP)nanofiberandfluoresentpoly(4-vinylpyridine)/porphyrin(P4-VP/TPPA)nanofiberwererespectivelypreparedbyelectrospinning.TheeffectoftheconcentrationofP4-VP/dimethylformamide(DMF)electrospinningsolutionsonthemorphologyofP4-VPnanofiberwasinvestigatedanditwasfoundthattheaveragediameterofthenanofiberofP4-VP/DMFincreasedwiththeincreaseoftheconcentrationofthespinningsolution.AftertheadditionofTPPAtotheP4-VP/DMFspinningsolution,thediameterofP4-VP/TPPAnanofiberbecameevenduetotheincreaseoftheconductivityoftheP4-VP/DMF-TPPAsolution.Thephotoluminescent(PL)spectralanalysisindicatesthattheemissionpeakpositionofP4-VP/TPPAnanofiberisalmostthesameasthatofpureTPPAatabout650nmwithoutpeakshift,andwhenitwasstoredfor20days,theemissionpeakofP4-VP/TPPAnanofiberisalsoat650nm,indicatingthatthefluorescentpropertyofP4-VP/TPPAnanofiberisstable.Fourier-transforminfrared(FTIR)spectrumconfirmsthechemicalcompositionoftheresultingP4-VP/TPPAcompositenanofiber.
简介:Bilayerhumidity-responsiveactuatorsaregenerallycomposedofactuatingandsupportinglayersofdifferentmaterialswithlargelydifferentwettability.Suchkindsofbilayeractuatorssufferfromlowadhesiveforcebetweenthetwolayersduringusage.Thisstudydemonstratesthepreparationofhumidity-responsivebilayeractuatorsthathavethesamematerialsintheactuatingandsupportinglayerstoavoidtheadhesiveissue.Thebilayeractuatorsconsistofaporouspoly(acrylicacid)σAA)/poly(allylaminehydrochloride)(PAH)layerandanonporousPAA/PAHlayerthatarefabricatedbyexponentiallylayer-by-layerassemblymethod.Atahigh/lowrelativehumidity(RH),thenonporousPAAIPAHlayercanefficientlyexpand/shrinkbyabsorbing/desorbingwaterwhilethevolumeexpansion/shrinkageoftheporousPAA/PAHlayerinanenvironmentwithchangedhumidityissignificantlysuppressedbythemicrometer-sizedpores.Thelargelydifferentexpansion/shrinkageofthenonporousandporousPAA/PAHlayerswhensubjectedtohumiditychangesenablesrapidandreversiblerolling/unrollingmotionsofthebilayeractuator.Thebilayeractuatorshowsafasterrollingspeedandalargerbendingcurvaturewhensubjectedtoalargerhumidityincrease.
简介:结晶化修正(vinylidene氟化物)(PVDF)poly为PVDF并且poly的混合电影(甲基methacrylate)(PMMA)被调查。集体crystallinity(c)并且进一步,阶段内容(PVDF的F()),与不同集体比率为asprepared混合电影被学习。另外,c和F的变化()一旦PMMA部件从相关混合系统被移开,系统地被探查。DSC,FTIR和XRD大小都显示了那1)c,F()并且甚至阶段的内容(F())与PMMA的增加减少了;2)与PMMA的抽取,c和F()当时,增加了F()减少。它是值得注意的c和F的增加()取决于提取PMMA(EPMMA)的相对数量,即,越多PMMA被移开,越多c和F()增加。这些结果从PMMA成分揭示阻碍者效果到PVDF的结晶化,并且因而,当PMMA被提取时,这限制将被释放。
简介:明显的antiplasticizing效果与MOCA的小数量在PVC被观察了,3,3-dichloro-4,4-diamino-diphenylmethane。PVC/MOCA混合的PVC-MOCA相互作用和结晶化行为详细被调查包括直接存储器存取,FTIR,和DSC根据一系列技术解释antiplasticization的机制。有MOCA的5phr的PVC的张力的力量到达的机械性质测试表演的结果最大的价值,69.5Mpa,它比纯PVC的高是大约23%。在张力的力量的上升在由直接存储器存取大小证实了的PVC上被归因于MOCA的antiplasticizing效果。从FTIR的证据表明一个强壮的结合氢的相互作用在MOCA和PVC重复单位的methine质子发生在-NH2组的氮原子之间。DSC分析的结果显示MOCA的那结晶化行为完全被压制,PVC的crystallinity随MOCA数量的增加减少。
简介:Lamellarcrystalsofdiblock,triblockandfour-armpoly(ethyleneglycol)-b-poly(ε-caprolactone)(PEG-b-PCL)crystalline-crystallinecopolymersweresuccessfullyobtainedfromtheirsolution.Morphologyandstructureoflamellarcrystalsofcrystalline-crystallinecopolymerswereinvestigatedusingtapping-modeatomicforcemicroscopy(AFM)andselectedareaelectrondiffraction(SAED).Allofthesesamplesshowedthetruncated-lozengemultilayerbasalshapeswithcentralscrewdislocationorcentralstack,whichwereallobtainedsimultaneouslyfromtheoilbath.ThediffractionpatternofPEGblocklamellarcrystalisattributedtothe(120)diffractingplanesandthepatternofPCLblocklamellarcrystalisattributedtothe(110)diffractingplanesand(200)diffractingplanesaccordingtotheSAEDresults.Four(110)crystalgrowthplanesandtwo(200)crystalgrowthplanesarediscoveredforthePCLblocks,butthe(120)crystalgrowthplanesofPEGblocksarehidedinthefigureofAFM.Thecrystallinestructureofthefour-armcopolymers(FA)ismoredisorderandconfusedthanthatofthediblock(DI)copolymerandthestriatedfoldsurfacestructuresoflamellarcrystalsoffour-armcopolymers(FA)aresmootherthantheseoflinearanalogues,owingtotheconfusedcrystallizationofblockscausedbythemutualrestrictionofblocksandthehindranceofthedendriticcores.Inaddition,theaspectratioofFAisgreaterthanthatoftheothers.Itishypothesizedthattherearetworeasonsforthechangeofaspectratios.First,the(200)diffractingplanesofPCLcrystalsgrewslowlycomparedtotheir(110)diffractingplanesbecauseofdifferenceintheenergybarrier.Secondly,edgedislocationsonthe(200)diffractingplanesarealsoresponsibleforthevariationoftheaspectratio.Consequently,thecrystallinedefectsareaugmentedbythecompetingblockscrystallizedsimultaneouslyandthehindranceofthedendriticcores.
简介:Inordertoimprovetheflexibilityofpoly(propylenecarbonate)(PPC),poly(1,2-propylenesuccinate)(PPSu)wasusedtoplasticizePPCinabatchmixer.TheeffectsofPPSuonthemiscibility,thermalstability,mechanicalandrheologicalpropertiesoftheblendswereinvestigated.PPCwaspartiallymisciblewithPPSu.ItwasdemonstratedthatPPSudecreasedtheglasstransitiontemperatureandmeltviscosityofPPC,asshownintheDSCandrheologicalcurves.WiththeincreaseinPPSucontent,thePPC/PPSublendsshoweddecreasedtensilestrength,however,theelongationatbreakwasincreasedto1100%forthe70/30PPC/PPSublend.TheintroductionofPPSuprovidedanefficientandnovelplasticizationmethodtoextendtheapplicationareaofPPC.
简介:Poly(aryleneetherdiketone)swerepreparedbythearomaticnucleophilicdisplacementreactionof4,4’-difluorobenzilwithdifferentbisphenolsinthepresenceofan-hydrouspotassiumcarbonateindiphenylsulfoneatelevatedtemperature.Thepolymersobtainedhadinherentviscosityof0.51~0.63dL/g,andexhibitedglasstransitiontemper-aturerangingfrom136~217℃mainlydependingonthebisphenolsusedinthepolymersynthesis.Thermogravimetryofthesepolymersshowedexcellentthermalstability,indi-catingthat10%weightlossesofthepolymerswereobservedintherangeabove428℃and438℃inairandnitrogen,respectively.ThemechanicalpropertiesofthesepolymerswerealsodescribedandthepermeabilityoffivepolymersforH2,O2andN2wasdeterminedat30℃.